In various commercial applications, such as in the manufacture of gas turbine engines, titanium-based alloys are used in the production of components therefor, such as fan discs and blades, compressor discs and blades, vanes, cases, impellers and the sheet-metal structure in the afterburner sections of these engines. In many of these applications, the gas turbine engine components of the titanium-based alloys are subjected to operating temperatures on the order of 950.degree. F. to 1000.degree. F. It is necessary that these components resist deformation (creep) at these high operating temperatures for prolonged periods of time and under conditions of stress. Consequently, it is significant that these alloys exhibit high resistance to creep at elevated temperatures and maintain this property for prolonged periods under these conditions of stress at elevated temperature.
Conventionally a titanium-based alloy having nominally, in weight percent, 6% aluminum, 2% tin, 4% zirconium, 2% molybdenum, 0.1% silicon, 0.08% iron, 0.11% oxygen and balance titanium (Ti6242-Si) is used in these applications, such as components for gas turbine engines, where high-temperature creep properties are significant. As turbine engine designers achieve improved engine performance, operating temperatures are correspondingly increased. Consequently, there is a current need for titanium-base alloys that will resist deformation at even higher operating temperatures, for example up to 1100.degree. F. and/or at higher stress levels than are presently achievable with conventional alloys, such as the alloy Ti-6242-Si. While it is important that the alloy retain resistance to deformation at elevated temperature for prolonged periods during use, it may also be important that sufficient room temperature ductility of the alloy be retained after sustained creep exposure. This is termed post-creep stability. Likewise, other mechanical properties, such as room and elevated temperature tensile strength, must be achieved at levels satisfactory for intended commercial applications.